Declaration

Syntax

All variables must be declared before they are used. In Mesham one may declare a variable via its value or explicit type.

var [varname];
var [varname]:=[Value];
var [varname]:[Type];

Semantics

The environment will map the identifier to storage location and that variable is now usable. In the case of a value being specified then the compiler will infer the type via type inference either here or when the first assignment takes place.

Note: It is not possible to declare a variable with the value null as this is a special, no value, placer and as such has no type.

Examples

var a;
var b:=99;
a:="hello";

In the code example above, the variable a is declared, without any further information the type is infered by its first use (to hold type String.) Variable b is declared with value 99, an integer and as such the type is infered to be both Int and allocated on multiple processes.

var t:Char;
var z:Char :: allocated[single[on[2]]];

Variable t is declared to be a character, without further type information it is also assumed to be on all processes (by default the type Char is allocated to all processes.) Lastly, the variable z is declared to be of type character, but is allocated only on a single process (process 2.)